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1//===- darwin-aarch64 floating point env manipulation functions -*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENV_DARWIN_IMPL_H10#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENV_DARWIN_IMPL_H11 12#include "src/__support/macros/attributes.h" // LIBC_INLINE13#include "src/__support/macros/config.h"14#include "src/__support/macros/properties/architectures.h"15 16#if !defined(LIBC_TARGET_ARCH_IS_AARCH64) || !defined(__APPLE__)17#error "Invalid include"18#endif19 20#include <arm_acle.h>21 22#include "hdr/fenv_macros.h"23#include "hdr/stdint_proxy.h"24#include "hdr/types/fenv_t.h"25#include "src/__support/FPUtil/FPBits.h"26 27namespace LIBC_NAMESPACE_DECL {28namespace fputil {29 30struct FEnv {31 struct FPState {32 uint64_t StatusWord;33 uint64_t ControlWord;34 };35 36 static_assert(37 sizeof(fenv_t) == sizeof(FPState),38 "Internal floating point state does not match the public fenv_t type.");39 40 static constexpr uint32_t TONEAREST = 0x0;41 static constexpr uint32_t UPWARD = 0x1;42 static constexpr uint32_t DOWNWARD = 0x2;43 static constexpr uint32_t TOWARDZERO = 0x3;44 45 // These will be the exception flags we use for exception values normalized46 // from both status word and control word.47 // We add EX_ prefix to the names since macOS <math.h> defines OVERFLOW and48 // UNDERFLOW macros.49 static constexpr uint32_t EX_INVALID = 0x1;50 static constexpr uint32_t EX_DIVBYZERO = 0x2;51 static constexpr uint32_t EX_OVERFLOW = 0x4;52 static constexpr uint32_t EX_UNDERFLOW = 0x8;53 static constexpr uint32_t EX_INEXACT = 0x10;54 // __APPLE__ ARM64 has an extra flag that is raised when a denormal is flushed55 // to zero.56 static constexpr uint32_t EX_FLUSHTOZERO = 0x20;57 58 // Zero-th bit is the first bit.59 static constexpr uint32_t ROUNDING_CONTROL_BIT_POSITION = 22;60 61 // In addition to the 5 floating point exceptions, macOS on arm64 defines62 // another floating point exception: FE_FLUSHTOZERO, which is controlled by63 // __fpcr_flush_to_zero bit in the FPCR register. This control bit is64 // located in a different place from FE_FLUSHTOZERO status bit relative to65 // the other exceptions.66 LIBC_INLINE static uint32_t exception_value_from_status(uint32_t status) {67 return ((status & FE_INVALID) ? EX_INVALID : 0) |68 ((status & FE_DIVBYZERO) ? EX_DIVBYZERO : 0) |69 ((status & FE_OVERFLOW) ? EX_OVERFLOW : 0) |70 ((status & FE_UNDERFLOW) ? EX_UNDERFLOW : 0) |71 ((status & FE_INEXACT) ? EX_INEXACT : 0) |72 ((status & FE_FLUSHTOZERO) ? EX_FLUSHTOZERO : 0);73 }74 75 LIBC_INLINE static uint32_t exception_value_from_control(uint32_t control) {76 return ((control & __fpcr_trap_invalid) ? EX_INVALID : 0) |77 ((control & __fpcr_trap_divbyzero) ? EX_DIVBYZERO : 0) |78 ((control & __fpcr_trap_overflow) ? EX_OVERFLOW : 0) |79 ((control & __fpcr_trap_underflow) ? EX_UNDERFLOW : 0) |80 ((control & __fpcr_trap_inexact) ? EX_INEXACT : 0) |81 ((control & __fpcr_flush_to_zero) ? EX_FLUSHTOZERO : 0);82 }83 84 LIBC_INLINE static uint32_t exception_value_to_status(uint32_t excepts) {85 return ((excepts & EX_INVALID) ? FE_INVALID : 0) |86 ((excepts & EX_DIVBYZERO) ? FE_DIVBYZERO : 0) |87 ((excepts & EX_OVERFLOW) ? FE_OVERFLOW : 0) |88 ((excepts & EX_UNDERFLOW) ? FE_UNDERFLOW : 0) |89 ((excepts & EX_INEXACT) ? FE_INEXACT : 0) |90 ((excepts & EX_FLUSHTOZERO) ? FE_FLUSHTOZERO : 0);91 }92 93 LIBC_INLINE static uint32_t exception_value_to_control(uint32_t excepts) {94 return ((excepts & EX_INVALID) ? __fpcr_trap_invalid : 0) |95 ((excepts & EX_DIVBYZERO) ? __fpcr_trap_divbyzero : 0) |96 ((excepts & EX_OVERFLOW) ? __fpcr_trap_overflow : 0) |97 ((excepts & EX_UNDERFLOW) ? __fpcr_trap_underflow : 0) |98 ((excepts & EX_INEXACT) ? __fpcr_trap_inexact : 0) |99 ((excepts & EX_FLUSHTOZERO) ? __fpcr_flush_to_zero : 0);100 }101 102 LIBC_INLINE static uint32_t get_control_word() { return __arm_rsr("fpcr"); }103 104 LIBC_INLINE static void set_control_word(uint32_t fpcr) {105 __arm_wsr("fpcr", fpcr);106 }107 108 LIBC_INLINE static uint32_t get_status_word() { return __arm_rsr("fpsr"); }109 110 LIBC_INLINE static void set_status_word(uint32_t fpsr) {111 __arm_wsr("fpsr", fpsr);112 }113};114 115LIBC_INLINE int enable_except(int excepts) {116 uint32_t new_excepts =117 FEnv::exception_value_from_status(static_cast<uint32_t>(excepts));118 uint32_t control_word = FEnv::get_control_word();119 uint32_t old_excepts = FEnv::exception_value_from_control(control_word);120 if (new_excepts != old_excepts) {121 control_word |= FEnv::exception_value_to_control(new_excepts);122 FEnv::set_control_word(control_word);123 }124 return static_cast<int>(FEnv::exception_value_to_status(old_excepts));125}126 127LIBC_INLINE int disable_except(int excepts) {128 uint32_t disabled_excepts =129 FEnv::exception_value_from_status(static_cast<uint32_t>(excepts));130 uint32_t control_word = FEnv::get_control_word();131 uint32_t old_excepts = FEnv::exception_value_from_control(control_word);132 control_word &= ~FEnv::exception_value_to_control(disabled_excepts);133 FEnv::set_control_word(control_word);134 return static_cast<int>(FEnv::exception_value_to_status(old_excepts));135}136 137LIBC_INLINE int get_except() {138 uint32_t control_word = FEnv::get_control_word();139 uint32_t enabled_excepts = FEnv::exception_value_from_control(control_word);140 return static_cast<int>(FEnv::exception_value_to_status(enabled_excepts));141}142 143LIBC_INLINE int clear_except(int excepts) {144 uint32_t status_word = FEnv::get_status_word();145 uint32_t except_value =146 FEnv::exception_value_from_status(static_cast<uint32_t>(excepts));147 status_word &= ~FEnv::exception_value_to_status(except_value);148 FEnv::set_status_word(status_word);149 return 0;150}151 152LIBC_INLINE int test_except(int excepts) {153 uint32_t statusWord = FEnv::get_status_word();154 uint32_t ex_value =155 FEnv::exception_value_from_status(static_cast<uint32_t>(excepts));156 return static_cast<int>(statusWord &157 FEnv::exception_value_to_status(ex_value));158}159 160LIBC_INLINE int set_except(int excepts) {161 uint32_t status_word = FEnv::get_status_word();162 uint32_t new_exceptions =163 FEnv::exception_value_from_status(static_cast<uint32_t>(excepts));164 status_word |= FEnv::exception_value_to_status(new_exceptions);165 FEnv::set_status_word(status_word);166 return 0;167}168 169LIBC_INLINE int raise_except(int excepts) {170 float zero = 0.0f;171 float one = 1.0f;172 float large_value = FPBits<float>::max_normal().get_val();173 float small_value = FPBits<float>::min_normal().get_val();174 auto divfunc = [](float a, float b) {175 __asm__ __volatile__("ldr s0, %0\n\t"176 "ldr s1, %1\n\t"177 "fdiv s0, s0, s1\n\t"178 : // No outputs179 : "m"(a), "m"(b)180 : "s0", "s1" /* s0 and s1 are clobbered */);181 };182 183 uint32_t to_raise =184 FEnv::exception_value_from_status(static_cast<uint32_t>(excepts));185 int result = 0;186 187 if (to_raise & FEnv::EX_INVALID) {188 divfunc(zero, zero);189 uint32_t status_word = FEnv::get_status_word();190 if (!(FEnv::exception_value_from_status(status_word) & FEnv::EX_INVALID))191 result = -1;192 }193 194 if (to_raise & FEnv::EX_DIVBYZERO) {195 divfunc(one, zero);196 uint32_t status_word = FEnv::get_status_word();197 if (!(FEnv::exception_value_from_status(status_word) & FEnv::EX_DIVBYZERO))198 result = -1;199 }200 if (to_raise & FEnv::EX_OVERFLOW) {201 divfunc(large_value, small_value);202 uint32_t status_word = FEnv::get_status_word();203 if (!(FEnv::exception_value_from_status(status_word) & FEnv::EX_OVERFLOW))204 result = -1;205 }206 if (to_raise & FEnv::EX_UNDERFLOW) {207 divfunc(small_value, large_value);208 uint32_t status_word = FEnv::get_status_word();209 if (!(FEnv::exception_value_from_status(status_word) & FEnv::EX_UNDERFLOW))210 result = -1;211 }212 if (to_raise & FEnv::EX_INEXACT) {213 float two = 2.0f;214 float three = 3.0f;215 // 2.0 / 3.0 cannot be represented exactly in any radix 2 floating point216 // format.217 divfunc(two, three);218 uint32_t status_word = FEnv::get_status_word();219 if (!(FEnv::exception_value_from_status(status_word) & FEnv::EX_INEXACT))220 result = -1;221 }222 if (to_raise & FEnv::EX_FLUSHTOZERO) {223 // TODO: raise the flush to zero floating point exception.224 result = -1;225 }226 return result;227}228 229LIBC_INLINE int get_round() {230 uint32_t rounding_mode =231 (FEnv::get_control_word() >> FEnv::ROUNDING_CONTROL_BIT_POSITION) & 0x3;232 switch (rounding_mode) {233 case FEnv::TONEAREST:234 return FE_TONEAREST;235 case FEnv::DOWNWARD:236 return FE_DOWNWARD;237 case FEnv::UPWARD:238 return FE_UPWARD;239 case FEnv::TOWARDZERO:240 return FE_TOWARDZERO;241 default:242 return -1; // Error value.243 }244}245 246LIBC_INLINE int set_round(int mode) {247 uint32_t bit_value;248 switch (mode) {249 case FE_TONEAREST:250 bit_value = FEnv::TONEAREST;251 break;252 case FE_DOWNWARD:253 bit_value = FEnv::DOWNWARD;254 break;255 case FE_UPWARD:256 bit_value = FEnv::UPWARD;257 break;258 case FE_TOWARDZERO:259 bit_value = FEnv::TOWARDZERO;260 break;261 default:262 return 1; // To indicate failure263 }264 265 uint32_t control_word = FEnv::get_control_word();266 control_word &= ~(0x3u << FEnv::ROUNDING_CONTROL_BIT_POSITION);267 control_word |= (bit_value << FEnv::ROUNDING_CONTROL_BIT_POSITION);268 FEnv::set_control_word(control_word);269 270 return 0;271}272 273LIBC_INLINE int get_env(fenv_t *envp) {274 FEnv::FPState *state = reinterpret_cast<FEnv::FPState *>(envp);275 state->ControlWord = FEnv::get_control_word();276 state->StatusWord = FEnv::get_status_word();277 return 0;278}279 280LIBC_INLINE int set_env(const fenv_t *envp) {281 if (envp == FE_DFL_ENV) {282 // Default status and control words bits are all zeros so we just283 // write zeros.284 FEnv::set_status_word(0);285 FEnv::set_control_word(0);286 return 0;287 }288 const FEnv::FPState *state = reinterpret_cast<const FEnv::FPState *>(envp);289 FEnv::set_control_word(static_cast<uint32_t>(state->ControlWord));290 FEnv::set_status_word(static_cast<uint32_t>(state->StatusWord));291 return 0;292}293 294} // namespace fputil295} // namespace LIBC_NAMESPACE_DECL296 297#endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENV_DARWIN_IMPL_H298